Re: [TCLUG:12668] [OT] 4-channel MP3/CD-audio?

[Dave Erickson <gsa700@mediaone.net>]

Mike Hicks wrote:
> 
> After seeing the recent post that showed a couple of the flags available
> for CD audio (DATA, 4_CHANNEL, COPY_PERMITTED, PRE_EMPHASIS), I began
> wondering about 4-channel audio.  Has anyone ever come across a CD that
> actually has 4-channel audio?  I'm kind of guessing that radio stations
> at least occasionally broadcast 4-channel audio, but then I'm not
> sure..  That would make sense, since a lot of people listen in their
> cars, but I don't know if FM can even do 4 channels.
> 
> Anyway, if I ever actually came across a CD with 4-channel audio, would
> I be able to play back a ripped track through anything I have?  Could I
> make an MP3 out of that and play it back ? (well, provided I actually
> had a card that did 4-channel audio ;-)
> 
> Just some random questions..

Disclaimer= I am not an expert.

As I understand it, FM (Frequency Modulation) can not handle 4 channels.
FM radio is basically AM with some additional informations sent along
that tells the FM tuner the differences between the left and right
channels.

However, Dolby Pro-Logic Surround Sound is actually 4 channels of sound
encoded into 2-channels of audio. So you could theoretically receive a
Dolby encoded radio station (or CD) and listen to it on your computer.
You could then rip it down to mp3 but my feeling is that all surround
info would be lost in the ripping. Additionally you would need a Dolby
decoder in your computer and a 4-channel sound system (right, center,
left, and rear).

You could do it though! See Cambridge Soundworks/Creative for the
Hardware. As for the Linux software... ;)))

--
Dave Erickson
"I'm a great believer in luck, and I find
  the harder I work the more I have of it."
                         -- Thomas Jefferson